The present invention relates to a supply air system defined in the preamble of the first claim presented below for feeding air into large spaces, such as machine rooms in paper mills or de-inking plants.
A conventional supply air system comprises typically means for supplying supply air from the open air to the internal space, at least one blower, means for cleaning and/or for regulating a desired temperature of the air supplied to the internal space, and an air distribution plate or the like for evenly distributing the air, which is cleaned and/or regulated to a desired temperature, to the desired location.
The equipment of the supply air system was earlier generally arranged on the roof of the mill, or in some cases in the basement. It can be very difficult to find sufficiently suitable space for the equipment in a basement. Generally there is space on the roof, but often it is inconvenient to mount the air ducts, the heat transfer piping and the electrical cabling to the roof from different locations. Further the arrangement of heavy equipment on the roof may require extra support of the roof. However, the greatest problem may probably be that the maintenance of the equipment on the roof is inconvenient; depending on the weather conditions the maintenance can some times be almost impossible.
Previously the Finnish patent FI 97166 proposed to install the air treatment equipment on the wall of the machine room within a housing structure arranged between two vertical columns. Then an opening is made in the wall in the region of the upper part of the housing, and external air is.supplied to the housing through the opening. Air louvers and a radiator heating the supply air are fastened to the wall, at the level of the opening. A plurality of blowers is arranged in the air space of the housing below the opening. The blowers are mounted on a horizontal plane fastened to the wall. The bottom part of the housing forms an air chamber from which the treated air is fed into the machine room. In this case the wall between the air chamber and the machine room is formed by a perforated plate. In this solution the maintenance objects, filters, louvers, blowers, are mounted about 4 to 5 meters above the floor level of the machine room, which makes the maintenance of the equipment inconvenient. No solutions have been proposed regarding the noise problems caused by the blowers which are freely located in the housing.
Now the object of the present invention is to provide an improvement to the problems presented above.
The object is then particularly to provide a supply air system with easily accessible maintenance objects.
An object is also to provide a supply air system where the blowers can be easily provided with silencers and where the housing structures can be advantageously made sound-proof.
In order to achieve the above-mentioned objects the system according to the invention is characterised in what is presented below in the characterising part of the first claim.
A typical supply air system according to the invention is formed by two separate units, the supply air unit and the air treatment unit, which are interconnected by one, advantageously at least two air ducts.
Thus the supply air system can be advantageously formed by supply air unit modules, air treatment unit modules and duct modules, which can be separately transported to the installation site. On the installation site the modules can be mounted on top of each other, so that the air treatment unit is first mounted on the floor level or on any other bearing surface carrying the system. The ducts which interconnect the supply air unit and the air treatment unit, typically two ducts, are mounted on the air treatment unit or on its sides. The ducts can be fastened to floor level or to a suitable bearing support surface. Then the supply air unit is mounted on the ducts. Thus the machine room floor or another corresponding carrying support surface acts as the support surface for the whole system.
The whole supply air system is advantageously dimensioned so that it can be arranged between two columns in the machine room. The system is typically arranged between columns next to the wall in the machine room, but when required, it can be arranged between two freely standing columns.
The supply air system is typically arranged in the actual machine room on machine level or in the basement located below the machine room. The supply air system can. be arranged to blow air from both spaces into the machine room and/or basement.
An inlet opening is formed at the supply air unit arranged next to the wall, in order to feed external air to the internal space or to the supply air unit. A louver directing the air flow can be arranged at the inlet opening, in the actual opening, in front of the opening, or after the opening. To a supply air unit arranged freely between columns the air is supplied with a duct from a place which is best suited, through the wall or the ceiling.
Means are arranged in the air treatment unit for cleaning the air supplied to the internal space and/or for regulating the temperature to a desired level. Often this entails heating the external air to a suitable level with the aid of a heating radiator. In some cases it may be necessary that the air entering the supply air unit is cooled by a cooling radiator.
In the solution according to the invention the supply air unit is mounted above the air treatment unit, so that an air space is left between the units, in other words so that a so-called air chamber is formed between the units. Typically the top part of the air chamber borders to the supply air unit, its bottom part borders to the air treatment unit, its back side borders to the machine room wall or some other corresponding backing structure, and its sides border at least partly to the air ducts. Further, the front of the air chamber borders, at least partly, to an air distribution plate or the like which is permeable to air, and through which the treated air is supplied to the machine room. The air flow is generated by a blower or blowers which advantageously are located in the ducts interconnecting the supply air unit and the air treatment unit. Thus the duct walls at the same time form a sound insulating layer around the blower. The blower can be advantageously located in the upper part of the duct, so that there is space left for a silencer in the lower part of the duct.
The blowers mounted in the ducts are advantageously axial blowers. However, the air flow can be generated in the system also by one or more centrifugal blowers arranged e.g. in the supply air unit and arranged to blow air down towards the ducts.
The blower generates an air flow from the external air trough the supply air system and into the machine room. Then the air flows from the opening formed in the wall, through the supply air unit and towards the top part of the ducts connected to this unit, and further downwards via the blower in the duct, to the lower part of the duct. From the lower part of the duct the air flow turns to one side towards the air box in the lower part of the air treatment unit. From this air box the air flows upwards through the air treatment unit and into the air chamber between the different units.
When the air flow comes from the duct into the air treatment unit it makes generally a turn of 180 degrees, from a downward flow into an upward flow. In the air treatment unit the air flows through the currently used treatment device, such as a filter and/or a heat transfer radiator.
The treated air flowing to the air chamber flows through the air chamber and out from the box to the machine room, through a wall between the box and the machine room provided with openings or the like flow passages. Different guiding plates can be arranged in the air chamber in order to direct the air flow in a desired manner within the air chamber, for instance also toward the gap between the air treatment unit and the distribution plate.
Within the air chamber and above the air treatment unit there can be arranged a maintenance gallery, which typically is a grating withstanding walking on it. From the maintenance gallery the maintenance personnel can service the blowers via a manhole made in the duct, or the heating radiators via openings in the maintenance gallery.
The vertical wall between the air chamber and the machine room, which wall forms the actual air distribution plate of the system, can be advantageously made of one or more perforated plates, or of perforated plate sections fastened to each other, which perforated plates are arranged to be movable like a xe2x80x9csliding doorxe2x80x9d or a xe2x80x9ccommon doorxe2x80x9d in front of the air chamber. When the air distribution plates formed by perforated plates are in their place in front of the air chamber the air can flow from the air chamber into the machine room mainly only through the openings in the plate. During maintenance the air distribution plates can be pulled away from its position in front of the air chamber, so that a service person can service the devices in the system.
In the solution according to the invention the supply air unit can be formed of a horizontal box structure in which the walls toward the machine room can be lined so that they insulate sound. Correspondingly the devices in the air treatment unit can be arranged in a horizontal box structure, where the walls bordering to the air distribution box or other parts can be lined so that they insulate sound.